Mean girls already?!

I'm horrified to even admit this.. I saw my 3 year old and her friend being so mean to another little girl! The girls were playing at the park and another little girl came up and wanted to play with them and they kept saying she couldn't play with them and to go away. I felt so bad! I took my daughter aside and tried to tell her in private that she wasn't being nice and to play nice with the other kids. I didn't want to cause a scene and draw attention to it but had to do something.. I thought I had 10 years before dealing with this! I'm so scared this is how she behaves at school with her friend..

my odd first week of prek she was sat next to a "mean girl." the girl just kept telling my daughter to "stop looking at me." i said the same thing mean girls already? luckily now the mean girl has been nicer.

Yes, it's pretty common at that age. I would just keep talking to her and ask her how would she feel if it was her being excluded. Just keep it simple and tell her it's not a nice thing to do because it hurts their feelings.